Author Archives: D.P. Lyle, MD

About D.P. Lyle, MD

Author, Lecturer, Story Consultant

When Your Antagonist Goes Viral

When Your Antagonist Goes Viral
by DP Lyle

Imagine this: Your protagonist is faced with a deadly enemy that can’t be seen, felt, smelled, tasted. Undetectable until it’s way too late. Imagine victims dropping all around him, many with horrible and frightening symptoms and signs. Things like blotchy purple skin rashes, raspy, wheezy breathing, bloody vomiting and diarrhea, confusion or psychotic and aggressive behaviors. Yet the cause of all this mayhem is unseen, and unknown.



How do you identify such an enemy, or defend yourself from it?

Infectious diseases have terrorized the world for centuries. The Black Death was just one, the worst, of the plagues that swept through Medieval Europe. It killed one third, maybe one half, of Europe’s population. With many of the above symptoms. The meager state of medical care—-or understanding—in 1350 could do little. The church was equally impotent. 

Imagine the terror that gripped the entirety of Europe. What caused these horrible things to happen? Was it bad air, some miasma? Was it spread by one group or another? Was it punishment for your sins?

Where could you go to avoid the plague? What could you do to protect yourself and your family? Who could you turn to? What would you do if an infected stranger appeared at your door? Would you trust your local officials or pray to a God that let this happen? 

There were no heroes available at that time.

But there have been, and are, other plagues that are more modern and equally as deadly. The 1918 flu claimed millions of lives around the world. Now we have such pleasant afflictions as HIV, Ebola, and the Marburg virus. Besides, isn’t the coming Zombie Apocalypse due to an errant virus?

Scary stuff.


Plague Doctor


The Plague was caused by a bacterium that today is easily treated with antibiotics. Drugs that weren’t available in the 14th century. Okay, great, The Black Death can’t happen today. Not so fast. What about viruses? Things like Ebola and Marburg. We have little effective testament for these guys. So, a new Black Death is always possible. And as the world turns, new creatures are evolving. A series of simple mutations could easily produce the next pandemic and yet again kill off half the population. In fact, it probably will someday. History repeats itself.

And such an unseen enemy can make for a nearly perfect fictional antagonist. I mean, you can flash a mirror, or cross, at Dracula, or fire a silver bullet into the Wolfman, or simply run from Frankenstein—he wasn’t very fleet of foot. Godzilla stomping your city to rubble creates different, but not insurmountable, problems. 

But where do you hide from a virus? 

I’ve practiced medicine for over forty years and I can say without doubt that the greatest stress placed on any human is when they face death, disease, or injury. There are so many unknowns and the feeling of helplessness is universal. The same is true if the sufferer is a parent, child, or loved one. It produces anxiety on a very basic and visceral level.

This innate fear of death and disease is part of the human experience. And excellent fodder for thriller writing. Sure Frankenstein and Godzilla are scary, but what about an unseen, unavoidable, untreatable enemy? One that has no boundaries, permeating the air you breath, the water you drink, the loved one you hug. There is nowhere to hide since the miasma can creep beneath your door.

It doesn’t bite, or maul, or stomp, or any of those physical things, but rather attacks from within. By the time the victim realizes something is wrong, it’s often too late to fix. Or worse, there is no fix.

Infectious processes have been the subject of many thrillers, both written and cinematic. Michael Crichton’s Andromeda Strain (1971) was an early example. An organism comes from outer space and kills quickly. Earthlings have no defense. Just as Europeans had no defense when the Black Death appeared. Others include The Cassandra Crossing (1976), 28 Days Later (2002), and Outbreak (1995).

Thrillers need a resilient, believable, relentless, deadly, seemingly-unstoppable antagonist. An unseen infectious creature that attacks from within fits the bill.

The Black Death:

1918 Flu:

Originally posted on the Horror Tree Blog:


Criminal Mischief: Episode #29: SKIN IN THE GAME

Criminal Mischief: Episode #29: SKIN IN THE GAME




Today, Tuesday, October 8, 2019 is the release date for the first story in my Cain/Harper thriller series: SKIN IN THE GAME.

For More Info and to Order:

Cain and Harper:

Raised as siblings by an itinerant “gypsy” family, knife expert Bobby Cain, trained by the US military in the lethal art of covert eliminations, and Harper McCoy, nurtured by the US Navy and the CIA to run black ops and wage psychological warfare, are now civilians. Of a sort. Employing the skills learned from the “family” and their training, they now fix the unfixable. Case in point: Retired General William Kessler hires the duo to track down his missing granddaughter, a Vanderbilt University co-ed. Their search leads them to a small, bucolic, lake-side town in central Tennessee and into a world of prostitution, human trafficking, and serial murder. The question then becomes: Will their considerable skills be enough for Cain and Harper to save the young woman, and themselves, from a sociopath with “home field” advantage, a hunter’s skills, and his own deeply disturbing agenda?



Cain returned home to collect Harper for the drive to Leiper’s Fork. A trip that raised ambivalent feelings. Sure it would be good to see General Kessler again. It had been many years. On the other side of the world, each with sand and grit in their hair, eyes, everywhere; Cain with fresh blood on his hands.

 But, under these circumstances? Kessler obviously adored his granddaughter. And with her parents succumbing to premature deaths, he and Miriam had essentially raised the girl. If she was truly missing, and not off on some college kid’s adventure, they would be crushed. Even a tough, old bird like Kessler.

 Cain heard the hiss of the shower coming from Harper’s room, indicating she had finished her workout. He knew she’d be ready to roll within minutes of stepping from beneath the spray. Harper wasn’t one to primp. Or waste time. 

Three years ago, a year after they had started their consulting—that nowhere near covered what they actually did—not sure there was a word for that—they had purchased the entire top floor of St. Germain Place. Before it was built out. They designed the space as a single unit with four bedrooms, an office, and a well-equipped gym that included a throwing area for Cain to remain proficient with his knives. A shooting gallery for Harper and her weapons would have been nice, but that would have violated a dozen city codes. It was all wrapped in 360- degree views of the city’s heart, the football stadium, and the Cumberland River. 

“What’s this about?” Harper asked as Cain pulled from the underground parking. 

He had called her as he left Milner’s office, telling her to get ready for a road trip. Probably just for the day but, as usual, to prep for a couple of more. You just never knew. 

“Cindy Grant. General Kessler’s granddaughter has gone missing.”

“Gone missing in a bad way?”


Cain avoided the interstate, as traffic there was unpredictable and most often snarled, instead following a more direct route. Highway 431, then 46, which melted into the one-street village of Leiper’s Fork. Calling it a village was a stretch, the “downtown” area being a couple of blocks long and the stores and restaurants sparse. Beyond, the highway resumed, becoming Old Hillsboro Road, a two-lane blacktop that wound through rolling fields and thick stands of pines and gums and oaks. A half mile south of town, General William Kessler’s estate came into view. 

“Impressive,” Harper said.

 As Milner had described, its stone construction brought to mind a medieval castle. Backed up against a hillock of dark-green pines, it possessed a commanding view of the General’s acreage, plenty of that, and the valley below. Civilian life had been good to the Kesslers. Cain knew their money had come from real estate and shrewd investing. Not to mention the various boards the General sat on. 

They were buzzed through the gate that stretched between two thick river rock columns and continued up 200 yards of winding drive that ended at a paved parking circle. A stone archway led to a pair of massive wooden entry doors. As Cain reached for the buzzer, one door swung open. 

Miriam Kessler. Thin, gray hair trimmed short, she wore black slacks and a lemon silk shirt. Cain knew she was sixty-eight but she appeared a dozen years younger. Less so today. Miriam had been at the General’s side through everything. Countless state dinners and military processions. Now she devoted her time to charities and fundraising. “Bobby Cain,” she said. “It’s been a long time.”

“How are you, Miriam?” They hugged.

“We’ve definitely been better.” 

“I don’t think you’ve met my sister, Harper.”

“I’ve heard about you though,” Miriam said, shaking Harper’s hand. “Please, come in.” Cain and Harper entered and she closed the door.

“Thank you for coming,” Miriam said. “On such short notice.”

“Anything for the General.”

“It’s been a tough week,” Miriam said. “Bill is beside himself.”

Cain remembered Miriam as always appearing fit, healthy, alive. Now, she wore a haggard, exhausted mantle. Stress lines cut into her face, her hair gray and tired. Her eyes held an irritated redness and a hint of puffiness. She looked like someone enveloped in a personal hell. Yet through that mask a glow of strength and resiliency persisted. Like so many military wives, she was a warrior. 

“Bill’s in his study.” 

She led them through a voluminous foyer and into a great room, which was exactly that. Ceilings that soared 25 feet above them, maybe more, and a massive stone fireplace, large enough to park a car inside. Plush sofas, antiques everywhere, and twenty-foot windows filling one wall. 

“Can I get you something?” she asked over her shoulder. “I’m sure Bill will want some lemonade.” 

“That would be fine,” Cain said.

 They entered the General’s equally impressive study. Kessler stood and came around his desk, hand extended, now silhouetted against cathedral windows that looked out over rolling hills of green grass and wads of thick pines. He wore gray slacks and a dark blue shirt. His hair silver, eyes deeply blue.

 “Bobby Cain,” he said. “It’s been a long time.”

“Yes, it has.”

They shook hands. Cain introduced Harper and they took seats facing Kessler who again settled into his oxblood leather chair.

“Wish it were under better circumstances,” Kessler said. “Did you have any trouble finding us?”

“None at all.”

“Good, good.”

Miriam returned with three glasses of lemonade.
“Anything else?” she asked.

“No,” Kessler said. “Thanks.” He offered her a sad smile.

“Then I’ll leave you to talk business.”

Kessler watched her go, waiting until the door closed behind her. “She’s taking this harder than me. And that’s pretty hard.”

“I imagine so,” Cain said.

“You know about loss.”

Cain stared at him.

“First being abandoned at—what was it? Two months?”

“That’s what I was told.”

“The murder of your adoptive parents. While you were overseas.” Cain nodded.

“And you, Harper. Abandoned, actually sold, by your mother.”

“You’ve done your homework,” Cain said.

 “As I’m sure you have. And will.” Kessler studied them for a beat, sighed. “The upshot is that I know each of you understand loss.”

 “From what I was told, your granddaughter is missing,” Harper said. “That doesn’t mean something has happened to her.”

 “I wish that was true.” He folded his hands before him. “But I’m a pragmatic man. Always have been.” He glanced at the door again. “I know the odds of her being alive are remote. Essentially nonexistent. It’s been a week now and she hasn’t responded. Her cell phone no longer receives calls. Something has happened. Something…unpleasant.”

 Cain wanted to reassure him but knew he really couldn’t. Mainly because the odds dictated he was correct. Still, he tried. “She’s a college kid. They do stupid things all the time. Like going away and forgetting to call.”

 “Not Cindy. Even when she was in Europe a couple of years ago, she called. Every day. Like clockwork. It’s in her nature.”

 “Do you have any evidence that something’s happened?” Harper asked.

 “Specifically? No.” Kessler shook his head. “I did call her roommate. A girl named Kelly Whitt. She said Cindy told her she was going to Colorado for a few days. She hasn’t heard from her since she left.”

 “Did she?” I asked. “Go to Colorado?”

 “She didn’t fly. Or take a train. Or rent a car, or use any of her credit cards. And her cell phone went out after about forty-eight hours. It’s last known position was in Nashville.”

 Cain was impressed, but not surprised. A retired General who had spent much of his life in intelligence, who ran dark ops in many of the most treacherous places on Earth, could get his hands on just about any information he needed.

 “Milner was a bit cryptic when we spoke. Exactly why are we here?” Cain asked.

 “Because I want you to find her. Or discover what happened to her.” He hesitated. “And make things right.”

 “I’m sure Milner told you that we don’t do missing persons.”

 Kessler leaned back in his chair, spun it slightly so he could gaze out the windows for a beat. He sighed; a deep, mournful sigh. “Let me ask you something,” He swiveled back around. “How many knives do you have on you right now?”

 “That you could find? Three or four.”

Kessler nodded. “The tools of your trade.”

Cain remained silent.

“Let me tell you a story,” Kessler said as he leaned back. “There was boy. Raised by a wandering gypsy band. Became an expert with knives. At a very early age. He put on knife throwing exhibitions all over the South. Part of the traveling show. He also became an expert second-story thief. He had many talents.” He steepled his fingers before him. “An arrest, an orphanage, and an adoption followed. Then on to the US Army. He was eighteen.” He scratched the back of one hand and then re-steepled his fingers. “His military career was destined to be bland, normal. But then his SEREs training drew some attention. If memory serves, he stayed off the radar for a week. And then suddenly appeared in his CO’s office. Something like that, anyway.” Kessler offered a half smile. “Ruffled more than a few feathers.”

 Kessler had definitely done his due diligence.

 “But our hero’s shenanigans attracted the attention of the Pentagon, a few other agencies. And his military career took a sudden turn. Ranger School, Seal and Delta training, followed by various Special Ops missions. Intelligence gathering, communication and supply disruptions, and a few targeted eliminations. Most, but not all, sanctioned.” He held Cain’s gaze a beat. “Yet, each necessary.” Kessler leaned back again, arms folded over his chest. “Then his parents were murdered. By three men. Each later met an unexpected and not so pleasant demise.”

 Again, Cain said nothing.

 “Our protagonist in this little tale then left the military. But not, for lack of a better term, special ops. Only his employers changed. Private, rather than military. His methods? Well, let’s just say the military—his gypsy family, too—trained him well.”

 Still, Cain remained silent.

 “Then, there’s another tale. Child sold to an itinerant family. By her alcoholic, half- Cherokee mother. Smart, precocious. Family disrupted when their past caught up to them. Orphanage, adoption, also military. Intelligence, PsyOps, CIA. Our heroine proved quite adept at running off-the-grid ops. The kind that could slam you in front of a Senate subcommittee.” He gave a half shrug. “Then, a chance reunion. In a hell hole.” 

Cain wasn’t really surprised that Kessler knew his background in intimate detail. They had a history. Kessler had run several of Cain’s missions. But Harper? Kessler didn’t know her. No military connection. Yet, Kessler had gone deep.

 “So, let’s get down to it,” Kessler said. “I know—I can feel it in my bones, and my bones are always right—that I will never see Cindy alive again.” Another glance toward the door. “I know that for a fact. She didn’t run off somewhere. Forget to call. This isn’t money driven. Not a ransom. This is something much worse. More final.”

 “Are you sure we’re the right people for the job?” Cain asked.

 Kessler leaned forward, his fists balled on his desk before him. “We’re soldiers. Each of us. Trained to do the tough jobs. The ones no one else will do.” He locked on Cain. “I know about Afghanistan. I know about the ones that killed your family in Tyler, Texas.” Now, his attention turned to Harper. “I know about deeply secret CIA ops. Most well below the threshold of visibility. I know much of the work you’ve done together over the past few years.” His fists relaxed. “So, yes, you’re the ones for this mission.”

 Mission? Interesting word choice. But not unexpected coming from Kessler.

Cain nodded. “What do you want us to do?”

Kessler’s blue eyes took on an extra intensity. “This is a military operation. A war, if you will. One where we, not the enemy, dictate the rules of engagement. You know me. Know I’m more of the General George S. Patton school. Stonewall Jackson, too. Never wait. Take the battle to the enemy. I want Cindy found. Dead, alive, whatever, I want her found. I want those who took her to feel the full weight of their actions. If she’s been harmed, I want those responsible harmed. If she’s been tortured, then pain and mortal fear should come their way. If she’s been murdered, I want them to suffer a similar fate.” His face darkened. “That’s what I want.” 

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Posted by on October 8, 2019 in Writing


SKIN IN THE GAME is Coming 10-8-19 With Some Fun Events


SKIN IN THE GAME, the first Cain/Harper thriller, is coming October 8th. 

Details and Order Info:

Who are Bobby Cain and Harper McCoy?

Raised as siblings by an itinerant “gypsy” family, knife expert Bobby Cain, trained by the US military in the lethal art of covert eliminations, and Harper McCoy, nurtured by the US Navy and the CIA to run black ops and wage psychological warfare, are now civilians. Of a sort. Employing the skills learned from the “family” and their training, they now fix the unfixable. Case in point: Retired General William Kessler hires the duo to track down his missing granddaughter, a Vanderbilt University co-ed. Their search leads them to a small, bucolic, lake-side town in central Tennessee and into a world of prostitution, human trafficking, and serial murder. The question then becomes: Will their considerable skills be enough for Cain and Harper to save the young woman, and themselves, from a sociopath with “home field” advantage, a hunter’s skills, and his own deeply disturbing agenda?


Terrific—truly sinister, scary, and suspenseful. Lyle never lets you down.—Lee Child, NYT Bestselling author of the Jack Reacher series

SKIN IN THE GAME hums like a tuning fork in perfect thriller pitch. Heroes Bobby Cain and Harper McCoy are skilled with blade and mind, and the villain here sent chills up my spine from page one on. This is further proof that Doug Lyle is at the top of his game.–T. Jefferson Parker author of THE LAST GOOD GUY

D.P. Lyle’s novels are chillingly authentic. An expert technician just keeps getting better. Packed with edge of the seat tension, Skin in the Game takes hunting to an astonishing, and frightening, new level.—Robert Dugoni, New York Times Bestselling Author of the Tracy Crosswhite Series

Skin in the Game is a bracing and blisteringly original thriller that challenges old genre rules while making up plenty of its own. D. P. Lyle has a fashioned a tale sharply edged enough to leave our fingers bleeding from turning the pages as fast as we can. His intrepid protagonists are among the best drawn and richly realized of any heroes seen in years with echoes of both David Baldacci and C. J. Box, making Skin in the Game is a winner from page one. A smooth and sultry tale that shoots for the moon and hits a literary bulls-eye.–Jon Land, USA Today bestselling author of the Caitlin Strong series 

Unputdownable. Bobby Cain wields both his knife and tongue with lethal expertise. Lyle’s seamless prose, gritty voice, and whiplash pacing culminate in an unforgettable climax, showcasing a heart-wrenching exposé into the world of human trafficking. And what a wild ride along the way. Ray Donavan meets Deliverance!—K.J. Howe, international bestselling author of SKYJACK 

SKIN IN THE GAME is “The Most Dangerous Game” on steroids. Fast, relentless, and cunning.—David Morrell, New York Times bestselling author of Murder As A Fine Art

DP Lyle writes wonderfully and with real insight.  He’s a born storyteller.–Peter James, bestselling author of the Roy Grace thriller series

Upcoming SKIN IN THE GAME Events

Join me for one or more of these if you can.

Thorne and Cross: Haunted Nights LIVE! Interview
Authors on the Air Network
Thursday, October 3, 2019, 5:00 p.m. PST–dp-lyle-joins-thorne-cross-haunted-nights-live

Mystery Ink, Huntington Beach, CA
Sunday, October 6, 2019, 3 p.m.
Mystery Ink Bookstore
8907 Warner Ave. #135
Huntington Beach, CA

Book Carnival, Orange, CA
Sunday, October 13, 2019, 3 p.m.
348 S. Tustin Street
Orange, CA

Lit Up! OC: Reading from SKIN IN THE GAME
Tuesday, October 22, 2019, 7 p.m.
Bardot Bars & Coffee
662 El Camino Real
Tustin, CA

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Posted by on September 30, 2019 in Writing


Criminal Mischief: Episode #28: The MacGuffin

Criminal Mischief: Episode #28: The MacGuffin






What is a MacGuffin? Since Alfred Hitchcock coined the term, his definition—such as it is—might be best:

“The main thing I’ve learned over the years is that the MacGuffin is nothing. I’m convinced of this, but I find it difficult to prove it to others.”



The Military Secrets in THE 39 STEPS

The Maltese Falcon in THE MALTESE FALCON


The briefcase in PULP FICTION

The Letters of Transit in CASABLANCA

The Ring in the LORD OF THE RINGS Trilogy

The Death Star Plans in STAR WARS


The Arc of the Covenant in RAIDERS OF THE LOST ARK

The Genesis Device in STAR TREK2: THE WRATH OF KHAN


Colonel Kurtz in APOCALYPSE NOW


The shark in JAWS

Doug the groom in THE HANGOVER


John Conner in THE TERMINATOR series





Suspected murder in REAR WINDOW


Strand Magazine: The Care and Feeding of a MacGuffin:

Wikipedia: MacGuffin:

Alfred Hitchcock Explains the Plot Device He Called the “MacGuffin”:

What Is A McGuffin?

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Posted by on September 24, 2019 in Writing


Franken-Mosquitoes Are Coming


Do you know what the most dangerous creature in the world is? The one that has been responsible for more human deaths and illnesses than any other?

The mosquito. And it’s not even close.

They’ve brought us such pleasant surprises as malaria, yellow fever, the Zika virus, Dengue Fever, Sleeping Sickness, Chagas Disease, West Nile virus, and a bunch of other diseases you’ve probably never heard of. The number of illnesses and deaths ascribed to these various diseases is nothing short of staggering.

And now scientists have genetically altered the mosquito in the hopes that they would help lower the mosquito population. You see, these new “:Franken-mosquitoes” were supposed to die quickly. Didn’t happen, and even worse, these genetic changes just might make them harder to kill. Which means that the lowly, annoying mosquito could be an even more powerful disease transmitter. File this under unintended consequences.

Bugged Out:

WHO Executive Summary on Insect-borne Diseases:


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Posted by on September 19, 2019 in Medical Issues


Jake Longly Is Coming To Germany


Fun and welcome news: Just signed the contracts to bring Jake Longly and crew to Germany. DEEP SIX, A-LIST, and SUNSHINE STATE will be translated and released in an e-format soon. Hope all my German friends and fans have fun hanging with Jake, Nicole, Ray, and Pancake. 


DEEP SIX Details:

A-LIST Details:


RIGGED, Jake Longly #4, is coming May, 2020:

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Posted by on September 16, 2019 in Writing


Criminal Mischief: Episode #27: ABO Blood Typing

Criminal Mischief: Episode #27: ABO Blood Typing






ABO Blood Type System


By simply typing the blood at a crime scene, investigators narrow their suspect list and completely exonerate some suspects by using the population distribution information for the four ABO blood types. 

Population Distribution of ABO Blood Types

O: 43%

A: 42%

B: 12%

AB: 3%

Besides determining the ABO type, serologists are able to further individualize blood samples. RBCs contain more proteins, enzymes, and antigens than those used in the ABO classification system. These include antigens with such catchy names as Duffy, Kell, and Kidd and intracellular enzymes such as adenylate kinase, erythrocyte acid phosphatase, and the very useful phosphoglucomutase (PGM).

PGM is an enzyme that appears in many different forms, or isoenzymes, and at least ten of them are fairly common. Regardless of ABO type, a particular individual can have any combination of the isoenzymes of PGM. The ME and the serologist use that fact to further narrow the list of suspects for further DNA analyses and confirmation that they were capable of leaving a particular bloodstain.

For example, say that a stain is Type AB and has PGM 2. The ME knows the AB blood type is found in only 3 percent (see Table 14‐1) of the population, and PGM 2 is found in only 6 percent of people. Because these two factors are inherited independently, the probability of a particular individual being Type AB, PGM 2 is only 0.18 percent or less than 2 per 1,000. 

If the police find blood at the scene that matches the blood of a suspect who has Type AB, PGM 2 blood, the probability that that suspect is not the perpetrator is 2 in 1,000. Although not perfect, those odds still are much better than a coin toss. 

Testing for Paternity 

You inherit your blood type from your parents. For that reason, a serologist can assess paternity in many cases. The crime lab is often involved in paternity testing because paternity may be a critical component in determining child support, custody, and visitation. It also may play an important role in crimes and civil proceedings that involve kidnappings, insurance fraud, and inheritance conflicts. 

Inheriting your blood type 

ABO blood types, or phenotypes, come in only four varieties: A, B, AB, and O. But, for some blood types two genotypes, or gene pairings, are possible. A phenotype is what something looks like (in this case the ABO blood type), while the genotype is the underlying genetic pattern. We receive our ABO genes from our parents, one from Dad and one from Mom. 

The important thing to know in this system is that A and B genes are co-dominant (equally dominant), while the O gene is recessive. So someone who receives an A gene from one parent and an O gene from the other has Type A blood, but not Type O, because the A gene is dominant. 

Determining Possible Genotypes from Phenotypes 

Type A: AA or AO

Type B: BB or BO

Type AB: AB

Type O: OO

People with Type O blood must have an OO genotype. They can have neither an A nor a B gene because having one or the other dominates the O gene and produces either Type A or Type B blood. 

A person with Type A blood can either receive an A gene from each parent and thus have an AA genotype or an A gene from one parent and an O gene from the other for an AO genotype. Remember, A is dominant, so when it is paired with the recessive O gene, the A gene determines blood type. People with the AA and AO genotypes both have Type A blood, but genetically speaking, they’re different. 

Type A parents who have AA genotypes can provide only A genes to their offspring, because all their eggs or sperm have an A gene. But Type A parents who have AO genotypes can provide either an A gene or an O gene to their offspring, because half their eggs or sperm have an A gene, and the other half have an O gene. When both parents are Type A, several possibilities exist for the genotype their offspring will have.

In each of the scenarios presented in Figure 14‐1, the child’s blood type is Type A, except when both parents donate an O gene. In the latter case, the child’s genotype and blood type (phenotype) respectively are OO and Type O. These parents can’t have any offspring who have Type B phenotype or BB, BO, or AB genotypes, because neither parent has a B gene to donate. 

Determining Fatherhood

Blood typing can exclude paternity but cannot absolutely verify it. For example, a man with Type AB blood can’t father a child with Type O blood. So if a child has Type O blood, all men with the Type AB are ruled out as the child’s father. A man with Type A (genotypes AA or AO) blood can be the father, but only if he has an AO genotype. Men who have AA genotypes also are excluded. Men with the AO genotype, however, can’t be ruled out at this point. 

To dig deeper into this complex system grab a copy of either:




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