8 doctors weighed in:
What are the genetics of sma?
8 doctors weighed in

Dr. Richard Roberts
Clinical Genetics
3 doctors agree
In brief: More than one type
Spinal muscular atrophy of infants, before the gene was identified, was called Werdnig-Hoffman disease.
Pitiful-we always looked at the tongues of floppy babies hoping it wasn't fasciculating. No treatment, breathing muscles progressively weakened, resulting in suffocation. 1 chance in 4 of recurrence-maybe. 2% were mew mutations. Kugleberg-Weilander disease had onset after 12 mo. Now 7 forms

In brief: More than one type
Spinal muscular atrophy of infants, before the gene was identified, was called Werdnig-Hoffman disease.
Pitiful-we always looked at the tongues of floppy babies hoping it wasn't fasciculating. No treatment, breathing muscles progressively weakened, resulting in suffocation. 1 chance in 4 of recurrence-maybe. 2% were mew mutations. Kugleberg-Weilander disease had onset after 12 mo. Now 7 forms
Dr. Richard Roberts
Dr. Richard Roberts
Thank
4 comments
Dr. Richard Roberts
The genetics is appallingly complex. In 1/50 of SMA-1, a spontaneous mutation is the cause, not found in a parent, and future sibs are not at risk. 3 forms are prenatal with death before or shortly after delivery. The genetics must be sorted out and appropriate genetic counseling given. Once identified, preimplantation diagnosis is possible. The 7 forms vary in age of onset, 7 being adult onset.
Dr. Richard Roberts
The genetics is appallingly complex. In 1 in 50 of SMA-1, a spontaneous mutation is the cause, not found in a parent, and future sibs are not at risk. 3 forms are prenatal with death before or shortly after delivery. The genetics must be sorted out and appropriate genetic counseling given. Once identified, preimplantation diagnosis is possible. The 7 forms vary in age of onset, 7 being adult.
Holly Barth
General Practice
2 doctors agree
In brief: Autosomal recessive
A defect in the smn1 gene is what is inherited.
Someone has to get 2 copies of this defective gene (one from mom and one from dad) to have sma. If someone only has one copy of the defective-they are a carrier and can pass on that gene to their offspring.

In brief: Autosomal recessive
A defect in the smn1 gene is what is inherited.
Someone has to get 2 copies of this defective gene (one from mom and one from dad) to have sma. If someone only has one copy of the defective-they are a carrier and can pass on that gene to their offspring.
Holly Barth
Holly Barth
Answer assisted by Holly Barth, Medical Student
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Dr. Diane Minich
Family Medicine
In brief: SMA
Spinal muscular atrophy (sma) is an autosomal recessive disease caused by a genetic defect in the smn1 gene that codes smn, a protein widely expressed in all eukaryotic cells.
The overall incidence of sma, of all types and across all ethnic groups, is in the range of 1 per 10, 000 individuals; the gene frequency is thus around 1:100, therefore, approximately one in 50 persons are carriers.

In brief: SMA
Spinal muscular atrophy (sma) is an autosomal recessive disease caused by a genetic defect in the smn1 gene that codes smn, a protein widely expressed in all eukaryotic cells.
The overall incidence of sma, of all types and across all ethnic groups, is in the range of 1 per 10, 000 individuals; the gene frequency is thus around 1:100, therefore, approximately one in 50 persons are carriers.
Dr. Diane Minich
Dr. Diane Minich
Thank
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